Film deposition apparatus



FILM DEPOS IT I ON APPARATUS Filed Aug. 1966 2 Sheets-Sheet l 57 l 1 18l; AFL 4 l f3/F] J 65 l 71; L 77 j z2 WWW Hr 1.9 i Jil 76 INVENTOR.

, WILLIAM I/.wsc'H .--r BY I, ,a6/J

April 2, 196s FILM DEPOS ITION- APPARATUS Filed Aug. 5, 1966 2Sheets-Sheet 2 INVENTOR. MLLIAM VRAUS'CH Mfw/ w. v; RAUSCH 3,375,804

Unite States This invention is concerned with deposition apparatus, andmore particularly with improved apparatus for providing high quality,lower cost deposition of films on a plurality of substrates.

The deposition of materials on a substrate, often referred lto as thinfilm deposition, is fast becoming Well known to those skilled in theart. In lilm deposition apparatus there is generally provided anevacuation chamber in which is mounted a melt. Thermal energy isprovided to the melt to cause it to give olf depositive vapors which areallowed to deposit on substrates placed in the vapor path. In thedeposition of magnetic films, a magnetic field is presented to the areaof deposition to cause the desired magnetic properties in the depositedlm. Various improvements in deposition, such as heating or preheatingsubstrates, providing cooling coils for maintaining desiredtemperatures, providing deposition monitor apparatus within theevacuative chamber, and others, have all added to the state of the artof film deposition.

One of the problems still present in the art is that of achieving massproduction of deposited substrates without affecting the quality of thedeposited film. The apparatus of this invention meets this problem byproviding increased deposited substrates per evacuation cycle, thuslowering substrate cost, yet maintaining a high quality of filmdeposition. Further, the unique apparatus of this invention provideshigh quality deposition, yet

reduces significantly the manual element in the deposition process.

Briefly described, the apparatus of this invention comprises acylindrical jar defining a vacuum chamber. A base plate and top plateare sealed to the jar to complete the chamber. Within the chamber, themelt is placed on a rotary melt support or pedestal, which can'comprisea rod extending from within the chamber at an end where the melt is heldto a point outside the chamber where the other end of the rod connectsto rotation members and to la coolingreservoir. Around the melt mountedon the rod is placed a substantially cylindrical substrate holdingmember. The longitudinal axis of this member is substantially in linewith the longitudinal axis of the r'nelt holding rod. This holdingmember is designed to l carry a plurality of substrates, which can bealigned in rows and columns. The mounting means for the substrateholding member are adapted to provide vertical motion to the holdermember so that a desired group of the plurality of substrates, such as asingle row of substrates, can be placed in depositive relation to themelt.

Shielding of the substrates other than the desired group is accomplishedby placing a second chamber Within the vacuum chamber, within whichsecond chamber the melt is disposed. In the preferred embodiment of thisyinvention described below, this second chamber comprises a pair ofhorizontally disposed substantially parallel plates. Apertures areprovided in the plates so that thermal energy from a member mounted inthe vacuum chamber can reach the melts, and so that a limited amount .p

of depositive vapors can reach monitoring apparatus also mounted in thechamber. Heating members and cooling coils are provided as required, asare magnetic lield coils when the deposition is to be a magnetic lm.

As the monitor indicates that deposition is completed ice on the firstdesired row of substrates, a device is actuated which moves thecylindrical substrate holder vertically to remove the depositedsubstrates from the second chamber and replace them with a seconddesired row of substrates.

As a further feature of this invention, the heating and cooling devicesare arranged such that the next succeeding row of substrates to receivedeposited vapors is preheated, while the completed deposited substratesare cooled. As a stil-l further feature of this invention, the secondchamber is designed such that the angle of incidence of the depositivevapors on the substrates is a maximum angle of approximately 79.

In the drawings:

FIGURE 1 is a sectional view of the deposition apparatus of thisinvention;

FIGURE 2 is a detailed partial sectional View of the rotary melt supportapparatus of this invention; and

FIGURE 3 is a perspective view of a substrate sled used with theapparatus of this invention, including an introrse view of a section ofthe substrate sled.

Referring tirst to FIGURE l, there is shown a substantially cylindricalvacuum jar 10, which can be of such material as non-magnetic stainlesssteel. A base plate 11 and a top plate 12 are placed at the ends of jar1l) and are sealed thereto, respectively, by O-rings 13 and 14. Whenthus connected, jar 10 along with plates 11 and 12 form a vacuum chamber26. A port 25 is provided in base plate 11 through which chamber 26 canbe evacuated by means of a pump i(not shown). Within chamber 26 there isshown mounted a rod 15, preferably of an oXygen-free-high-conductivitymaterial. =Rod 15 has an upper portion extending into chamber 26, theend of which carries a melt such as 16. The lower portion of rod 15extends through a feed-through 18, and into a cooling reservoir 19. Apreferred embodiment of feed-through 18 and reservoir 19 is discussedbelow in the description of FIGURE 2.

An electron gun 21 is mounted in top plate 12 and extends into chamber26. Electron gun 21 provides an electron beam, indicated by the dottedlines I22, which strikes melt 16 to provide thermal energy thereto. Thethermal energy results in meltY 16 emitting depositive vapors, indicatedby dotted lines 23. A first plate 27 is horizontally mounted on plate12, and extends horizontally above melt 16. A second plate 28 is mountedbelow melt 16 on plate 11, and extends substantially parallel to plate27. Plates 27 and 28 form a second chamber within chamber 26. It iswithin this second chamber that' the deposition process wi-ll takeplace, with most of de. positive vapors 23 being restrained between 27and 28.

An aperture 29 is formed in plate 27 to allow beam 22 from electron gun-21 to reach melt 16. There is also shown a deposition monitor 31mounted in chamber 26, and having electrical leads extendingthrough anelectrical feed-through 32 to outside the chamber. Another aperture 33is formed in plate 27 to allow a portion of depositive vapors 23 toreach deposition monitor 31.

Mounted between Aplate 27 and plate 12 there are shown a plurality ofthreaded rods 34. Shields 44 are provided around threaded members 34 toprevent deposition on the thread from interfering with movement ofholder 36. Threaded on rods 34 are a plurality of threaded sockets 35.Sockets 35 are connected to a substantially cylindrical substrate holder36. Threaded rods 34 extend through feed-throughs in plate 12 to idlersprockets such as 37.

The idler sprockets are connected by belt or chain 38 to a sprocketdrive motor 39. The energization of motor 39 will cause sprockets 37 toturn threaded members 34. This will cause vertical motion of sockets 35which will carry substrate holder 36 in a vertical direction.

A substrate sled 41, more fully seen in FIGURE 3, is

mounted on substrate holder 36. Substrate sled 41 carries a plurality ofrows of substrates such as 42. As substrate holder 36 is movedvertically downward by actuation of m-otor 39, the rows of substrateswill also move downward to remove one row of substrates from thedeposition area between plates 27 and 28, and place another row ofSubstrates 42 within the deposition area.

There is also shown a heater 46 in substantially cylindrical form andmounted around holder 36. Many thermal radiation sources can be used forheater 36 to provide a uniform and controllable temperature tosubstrates 42. For example, commercial quartz infra-red tubular elementsarranged in a vertical fashion to form a cylindrical heat source can beused for deposition Iof magnetic thin films. Heater 46 is of suchdimensions that in addition to heating the row of substrates 42undergoing deposition, it simultaneously preheats the next succeedingrow of substrates.

A plurality of cooling coils 47 are shown wrapped in helical fashionaround the external periphery of jar 10. Cooling coils 47 provideconduction of radiated thermal energy from the system. Wound Outside ofcooling coil 47 is a magnetic field winding 48. Winding 48 can providethe necessary orienting of the magnetic field when deposition ofmagnetic films is desired. Winding 25 is extended almost to base plate11 so that the deposited magnetic films remain in the orienting fielduntil adequately cooled.

Also shown mounted in chamber 26 on plate 27 is a thermocouple 51, whichhas electrical connections extending through an electrical feed-through52 in plate 12. Thermocouple 51 is a sliding contact therrnocouple formonitoring the temperature of substrates 42.

There is also shown mounted in chamber 26 a shutter 55, which isconnected to a push-pull rod 56 which exi tends through a slidingfeed-through 57 to outside chamber 26. Actuation of 4push-pull rod 56causes shutter 55 to selectively expose or shield melt 16, so thatdepositive vapors can be substantially removed from the area ofsubstrates 42 during vertical motion of holder 36, or at other desiredtimes. A shield 59 mounted on rod 15 helps to prevent downwardlyextending depositive vapors 23 from contaminating the apparatus.

Referring now to FIGURE 2, melt support 15 along with its rotaryfeed-through 18 and cooling reservoir 19 are more fully described. Hereit is seen that the lower end of rod 15 extends into a cooling reservoir19` which may contain a fluid such as water. Water input 76, and output77 are provided to allow a ow of water through reservoir 19. A bearing74, such as the Teflon bearing, is mounted between rod 15 and reservoir19, to allow for rotation of rod 15. A pulley 71 is attached to rod 15and is driven by belt or chain 72 connected to drive means (not shown)to provide a rotary motion to rod or melt support 15, such as in thedirection indicated by arrow 78. This rotary motion of rod 15 causes asimilar rotary motion of rod 16 to allow for even deposition onthecylindrical row of substrates 42.

Also in FIGURE 2 it can be seen that feed-through 18 comprises a rotary-feed-through 61 sealed to base plate 11 by an O-ring 62. The lowerportion of feed-through 61 is secured and sealed by an O-ring 63, apressure collar 64, and a Ipressure nut 65. Similarly, the upper end offeed-through 61 is sealed by an O-ring 66, a pressure collar 67, and apressure nut 68.

As mentioned above, rod 15 is preferably oxygen-free, and of a high heatconductivity material. The preferred embodiment shown in FIGURE 2 isonly one of many alternative methods of providing a rotatable cooledmelt support such as 15. For low-power operations, where the meltmaterials exhibit high vapor pressures, a feedthrough such as thatdescribed for -feed-through 18 can be used with anoxygen-free-high-conductive rod 15 which utilizes the cooling Waterreservoir 19. For high-power operations, such as evaporating refractorymetals, an arrangement similar to FIGURE 2 can be used if the coolingwater is forced through appropriate channels in rod 15 itself. However,for most materials, the apparatus of the preferred embodiment of FIGURE2 provides adequate cooling of the melt support 16.

In FIGURE 3 there is shown a substrate sled 41 which is mounted onsubstrate holder 36. It can be seen that sled 41 comprises asubstantially cylindrical polygonal figure. An ntrorse View of section41a and of sled 41 discloses that a plurality of substrates 42 aremounted on each side o-f sled 41, and can be held in place by clips suchas rotatable spring clips 43.

For better understanding of the operation of the apparatus of thisinvention, a complete, typical cycle for mass deposition of magneticfilm memory elements will now be described. For this description it isassumed that a removable and replaceable top plate 12 is used in theapparatus `of this invention, and that a plurality of such plates areavailable. To optimize the efficiency of the pumping station, twocomplete top cover plates, along with the electron gun and substrateholding member assemblies can be used.

A top cover plate 12 including all attached fixtures as shown in FIGUREl is removed from the chamber for l unloading of the deposited films,installation of monitor crystals in the vdeposition monitor 31, andloading of uncoated substrates. Substrate sleds 41 as shown in FIG- URE3, are removed from holding assembly 36, unloaded, and loaded withuncoated substrates and vapor shields.

The entire top cover plate unit is then reinstalled on jar 10, andevacuation of chamber 26 is accomplished through port 25.

The first cylindrical row of substrates 42 is in position fordeposition, as shown in FIGURE l, where the first row is aligned betweenplates 27 and 28. Substrates 42 of the first and second cylindrical rowsare brought to desired temperature by heater 46, and by supplying theappropriate amount of cooling water to cooling coils 47.

Shutter 55 is pushed into the closed position around melt 16, andelectron gun 21 is turned on to provide electron beam 22, to increasethe temperature of melt 16 to the temperature corresponding to thedesired deposition rate. Shutter 55 is then opened to allow thedepositive vapors 23 to reach the substrates in monitor 31. Condensationof the metallic depositive vapors upon the exposed row lof substrates 42and upon monitor. 31 then occurs. After the desired film thickness isobtained, as evidenced by deposition monitor 31, shutter 55 is againactuated to the closed position to prevent further deposition onsubstrates 42 and monitor 31, and electron beam 22 is defocused toreduce evaporation of melt 16.

Sprocket motor 39 is then `actuated to turnthreaded rods 34 to providedownward vertical motion to holder 36. 'Ph-is lowers substrates 42 untilthe next vsucceeding row of subst-rates is in the chamber formed byplates 27 and 28 and ready for deposition. Deposition monitor 31 isrezeroed at this time. Also, heater 46 will begin to preheat the lohirdrow of substrates 42.

After the second row` of substrates `reaches -the desired temperature,electron beam 22 is refocused and shutter 55 is again opened to allowdeposition of themagnetic film upon the exposed substrates of the secondcylindrical row, and upon monitor 31.

The above sequence is repeated until `all rows of substrates 42 havebeen coated. After the substrates and holding assembly have been cooledsufficiently, the entire top cover plate-fixture arrangement is removedand replaced with an identical system holding uncoated substrates. Theremaining melt material 16 Ican be removed and a fresh melt materialinstalled on melt support 15 prior to closing the chamber for anotherdeposition sequence.

Thus it is apparent that -the `above described apparatus provides aunique structure for mass production. of coated substrates, without lossof quality, in a single evacuation cycle.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. In deposition `apparatus `including a vacuum chamber, means forevacuating the chamber, and deposition monitor means, the improvementcomprising:

melt support means at least partially mounted in the chamber Iaround avertically extending longitudinal axis, said support means adapted tocarry a melt for forming depositive vapors;

means mounted in the chamber for providing thermal energy to the melt;

substantially cylindrical substrate holder means including substratesled mounting means on the inner surface of said holder means, saidholder means vadapted to carry substrate sleds having a plurality ofsubstrates mounted thereon;

means movably mounting said holder means in the chamber, thelongitudinal Vaxis thereof being substantially the longitudinal axis ofsaid melt support means; p

means for vertically moving said holder means, to sequentially move agroup lof said plurality of substrates into spaced relation with themelt for depositio-n on the group of substrates, and a pair of vapordeflection plates mounted in the chamber in generally horizontally,spaced relation, above and below the melt to shield the plurality ofsubstrates other than the group of substrates from depositive vaporsformed by the melt.

2. The apparatus of claim 1 in which said melt support means comprises:

feed-.through means mounted to said chamber;

an elongated rod mounted in said feed-through means and having an upperportion extending into the chamber for supporting the melt, and a lowerportion extending out of the chamber; and

cooling means mounted in contact with said lower portion of said rod.

3. The apparatus of claim 2 including:

means rotatably mounting said rod in said feed-through means; and

means connected to said lower portion of said rod for rotating said rodIaround the longitudinal axis.

4. The apparatus of claim 1 including:

movable shutter means mounted in the chamber;

means connected to said shutter means and extending out of said chamberfor selectively moving said shutter means to shield the substrates fromthe depositive vapors formed by the melt.

5. The apparatus of claimt 1 wherein said vapor deflecting plates aresubstantially parallel to one another.

6. The apparatus of claim 5` including:

a iirst aperture formed in said plates and aligned between said meansfor providing thermal energy and the melt; and .f

a second aperture formed in said plates and aligned between thedeposition monitor means and the melt.

7. The `apparatus of claim 5 in which:

the spaced lrelation of said substrate holder means and the melt, andthe spaced relation of said deector plates and the melt arepredetermined to provide a maximum angle of incidence of the depositivevapors on the group o-f substrates of approximately 7.

8. The apparatus of claim 1 including:

substrate heater means mounted external to and around the periphery ofthe chamber; and

said substrate heater means being of suflicient dimensions to heat thegroup of substrates undergoing deposition, and to preheat the nextsucceeding group of substrates.

9. The apparatus of claim 8 including:

magnetic field producing means mounted external to a-nd around theperiphery of the chamber to provide an orientin-g ield when magnetic lms.are being deposited; and

said magnetic field producing means being of suiicient dimension toprovide an orienting tield to the group of substrates undergoingdeposition, and to prior deposited groups of substrates while they arecoolmg.

10. In deposition apparatus including a vacuum chamber, means forevacuating the chamber, melt support means mounted in the chamber, andmeans for Vaporizing a melt supported by the melt support means, theimprovement comprising:

substrate holder means adapted to hold a plurality of substrates andcomprising an open-ended body of substantially cylindrical form, mountedwith its longitudinal axis in a substantially vertical disposition andpassing through the melt;

means mounting said substr-ate holder in the chamber and adapted toselectively move said substrate holder relative to the melt on the meltsupport means to place a desired group of said plurality of substratesin deposition relation with the melt;

a second chamber in the vacuum chamber;

the melt support means adapted to hold the melt in said second chamber;

the movement of said substrate holder adapted to place the desired groupof said plurality of substrates in said second chamber, so that saidplurality of substrates other than the desired group `are substantiallyshielded from the melt; and

said second chamber comprising a pair of spaced, generally horizon-tallydisposed plates mounted in the vacuum chamber above and below the melt.

11. The apparatus of claim 10 including the improved melt support meanscomprising:

a vertically extending rod having upper and lower portions;

means mounting at least said upper portion in the chamber, the end ofsaid upper portion adapted to support the melt; and

means connected to said lower portion for rotating said rod around itslongitudinal axis. 12. The apparatus of claim 10 in which:

thedimensions of said second chamber are predetermined to limit themaximum angle of incidence of depositive vapors from the melt on thesubstrates to approximately 7".

References Cited UNITED STATES PATENTS 2,369,764 2/ 1945 Ullrich 118-492,414,406 1/ 1947 Colbert et al. 11S-49 2,420,722 5/ 1947 Peterson etal. 118-49 2,421,343 5/ 1947 Mageoch. 2,453,582 11/ 1948 Morgan v 118-492,621,624 12/ 1952 Chilowsky 118-49 X 2.665,659 1/1954 Ogle 11S-492,768,098 10/ 1956 Hoppe 11S-49.1 X 2,796,041 6/ 1957 Banzhof 118-301 X2,801,607 8/1957 Vodar et al 11S-49.1 2,852,416 9/1958 McNary et al.118-49 X 2,912,351 11/1959 Danner et al. 11S-49.1 X 3,077,444 2/ 1963Hoh 118-490 XR 3,131,078 4/1964 Fuller et al 118-49.1 X

FOREIGN PATENTS 222,198 7/ 1962 Austria. 838,480 6/ 1960 Great Britain.

MORRIS KAPLAN, Primary Examiner'.

1. IN DEPOSITION APPARATUS INCLUDING A VACUUM CHAMBER, MEANS FOREVACUATING THE CHAMBER, AND DEPOSITION MONITOR MEANS, THE IMPROVEMENTCOMPRISING: MELT SUPPORT MEANS AT LEAST PARTIALLY MOUNTED IN THE CHAMBERAROUND A VERTICALLY EXTENDING LONGITUDINAL AXIS, SAID SUPPORT MEANSADAPTED TO CARRY A MELT FOR FORMING DEPOSITIVE VAPORS; MEANS MOUNTED INTHE CHAMBER FOR PROVIDING THERMAL ENERGY TO THE MELT; SUBSTANTIALLYCYLINDRICAL SUBSTRATE HOLDER MEANS INCLUDING SUBSTRATE SLED MOUNTINGMEANS ON THE INNER SURFACE OF SAID HOLDER MEANS, SAID HOLDER MEANSADAPTED TO CARRY SUBSTRATE SLEDS HAVING A PLURALITY OF SUBSTRATESMOUNTED THEREON; MEANS MOVABLY MOUNTING SAID HOLDER MEANS IN THECHAMBER, THE LONGITUDINAL AXIS THEREOF BEING SUBSTANTIALLY THELONGITUDINAL AXIS OF SAID MELT SUPPORT MEANS; MEANS FOR VERTICALLYMOVING SAID HOLDER MEANS, TO SEQUENTIALLY MOVE A GROUP OF SAID PLURALITYOF SUBSTRATES INTO SPACED RELATION WITH THE MELT FOR DEPOSITION ON THEGROUP OF SUBSTRATES, AND A PAIR OF VAPOR DEFLECTION PLATES MOUNTED INTHE CHAMBER IN GENERALLY HORIZONTALLY, SPACED RELATION, ABOVE AND BELOWTHE MELT TO SHIELD THE PLURALITY OF SUBSTRATES OTHER THAN THE GROUP OFSUBSTRATES FROM DEPOSITIVE VAPORS FORMED BY THE MELT.